1. Field of the Disclosure
This disclosure relates generally to drilling motors for use in drilling of wellbores.
2. Brief Description of the Related Art
To obtain hydrocarbons, such as oil and gas, boreholes or wellbores are drilled by rotating a drill bit attached to a drill string end. A substantial proportion of the current drilling activity involves drilling deviated and horizontal boreholes to increase the hydrocarbon production and/or to withdraw additional hydrocarbons from the earth's formations. Modern directional drilling systems generally employ a drill string having a drill bit at the bottom that is rotated by a positive displacement motor (commonly referred to as a “mud motor” or a “drilling motor”). A typical mud motor includes a power section that contains a stator and a rotor disposed in the stator. The stator typically includes a metal housing lined inside with a helically contoured or lobed elastomeric material. The rotor is typically made from a suitable metal, such as steel, and has an outer lobed surface. Some mud motors include a metallic stator and a metallic rotor. Pressurized drilling fluid (commonly known as the “mud” or “drilling fluid”) is pumped into a progressive cavity formed between the rotor and stator lobes. The force of the pressurized fluid pumped into the cavity causes the rotor to turn in a planetary-type motion. In the metal stator and metal rotor mud motor, a clearance is designed between the rotor and stator to allow assembly of the mud motor. The friction between the elastomeric stator and the metallic rotor results in loss of efficiency of the motor.
The disclosure herein provides drilling motors that include stators and/or rotors with a coating of a diamond-like carbon material.